You are building an application to track cell towers that are available to phones in near real time. A phone will send information to the application by using the Azure Web PubSub service. The data wi

You are building an application to track cell towers that are available to phones in near real time. A phone will send information to the application by using the Azure Web PubSub service. The data will be processed by using an Azure Functions app. Traffic will be transmitted by using a content delivery network (CDN). The Azure function must be protected against misconfigured or unauthorized invocations. You need to ensure that the CDN allows for the Azure function protection. Which HTTP header should be on the allowed list?